Many absorbent products, such as disposable diapers, sanitary napkins, and the like, include an absorbent panel. The absorbent panel is formed of loosely compacted short fibers, such as wood pulp fibers or cotton linters, or mixtures thereof, and the like. The panel is produced by taking a source of short fibers such as a pulp board and grinding the board and individualizing the fibers therein using a grinding mill. The individualized fibers are collected on a screen or other permeable means in the form of a layer or batt of loosely associated short fibers. The batt is usually lightly compacted to provide some integrity.
In some absorbent products, a panel of a specific size may be desired while in other absorbent products a panel of a specific size and shape may be desired. In the past, it has been the usual practice to sever sections from an absorbent batt by cutting the batt, as with a knife or scissors. Due to the loose structure of the fibers in such batts, this type of severance often results in permanent compression of the fibers at the severance line. As a result of this compression, the density of the fibers in this region is greatly increased and, consequently, the wickability or preferential absorptivity along the line of permanent compression is greatly increased. This result may be most disadvantageous in the formation of a diaper panel since urine will migrate along a line of densification that comes into contact with it. If this densification line occurs at an edge, as where the panel section has been cut with a knife edge, there is a strong tendency for any liquid coming into contact with the line to be drawn into and concentrated at the line, resulting in premature leakage of urine from the diaper structure. Furthermore, the above method of cutting the batt results in harshness of the batt at the compressed line.
Since the structure of absorbent batts is loose, these batts may be quite easily torn when stressed. Moreover, if the tearing can be done without compressing the fibers of the batt, no densification lines will be created at the edge. U.S. Pat. Nos. 3,895,751 and 3,957,186 disclose devices which tear a batt to form panels without creating densification at the tear line. The first-mentioned patent discloses an apparatus for tearing an intermittently fed batt wherein a pair of juxtaposed opposing jaws operate transversely on a batt to form panels. Each pair of jaws consists of a first jaw and a second biased hinged jaw, so that after the jaws grip the batt, the first jaw holds the batt and the second jaw is displaced from its juxtaposed position, thus tearing the batt transversely. The apparatus of the second patent consists of two opposed, rotatable pairs of batt-engaging cylinders comprising a trailing jaw member and a juxtaposed leading jaw member. The cylinders are simultaneously rotating in opposite directions. As the batt is engaged by the jaws, a displacing means, such as a cam, displaces one cylinder segment of each pair of cylinder segments relative to the other cylinder segments so that the batt is torn. In the instance of each patent there are pivotal means involving displacing jaws so that operational techniques require extra care in cleaning and maintenance and pivoting parts are easily worn.
Another technique for forming individual panels of loose fibers, which may be rectangular in shape or in other desired shapes, without forming the harsh compressed lines produced by cutting the batt is disclosed in U.S. Pat. No. 3,973,291 assigned to Scott Paper Company. In this patent, the panels are formed individually by air laying the fibers within a pattern of the desired size and shape. As described in the aforementioned patent, the machinery required to produce such individually air laid panels and convey such panels is quite large and cumbersome and relatively complex in its moving parts and operation.
Also in the co-pending, commonly assigned patent application Ser. No. 888,818 filed Mar. 21, 1978 issued U.S. Pat. No. 4,216,687 issued Aug. 12, 1980, there is disclosed an apparatus which utilizes air jets to shape and partition a loose batt of fibers into individual shaped panels. While the machine disclosed in the above-mentioned patent application is relatively simple in construction and operation, it does require means for generating an air supply and maintaining the air clean which is an added cost in the manufacture of the desired absorbent product.
In a further example, German Pat. No. 1,252,050 to Hesser, a device is shown for separating cardboard sections defined by lines of weakening from a continuous strip of cardboard. The section to be severed from the strip is held between a rubber bar and an underlying roller while the rest of the continuous strip is moved rearwardly by the action of a single, slideably-mounted segment of the underlying roller. In contradistinction thereto, the present invention provides a simple and economical method and apparatus for partitioning and/or shaping a continuously moving batt which is fed between a pair of rolls rotating in opposite directions. The rolls have engaging jaw members such that the batt is partitioned and/or shaped in a manner to provide clean lines with no densification of the batt material.